Control of the swashplate of a barrel pump by rocker-arms



April 28, 1964 Filed April G. BOULET 3,130,593

CONTROL OF THE SWASHPLATE OF A BARREL PUMP BY ROCKER-ARMS 2 Sheets-Sheet1 INVENT- OR GEDRGES BQUL'EI'T April 28, 1964 G. BOULET 3,130,593

CONTROL OF THE SWASHPLATE OF A BARREL PUMP BY ROCKER-ARMS Filed April19, 1962. 2 Sheets-Sheet 2 INV ENT OR GEORGES BOULET United StatesPatent 3,130,593 CONTROL or run SWASHPLATE OF A BL PUMP BY RocKER-ARMSThe present invention relates to barrel pumps in which an oblique plategoverns the travel of the pistons of the pump. In order to regulate therate of delivery and/ or the pressure supplied by the pump, it is wellknown that the obliquity of this plate must be made variable, and theinvention has for its object a system of control of this obliquity ofthe plate.

The control of obliquity of the plate according to the invention ischaracterized by the action on the plate of two rocker-arms which arethemselves mechanically operated, for example by the pistons of twojacks, by two push-rods, by two cams, etc., these rocker-arms being soarranged as to reduce the transverse friction to a minimum and tomaintain the lines of action of the forces in the vicinity of the axesof their mechanical controls.

One embodiment of the control according to the invention will bedescribed with reference to FIGS. 1 and 2 of the accompanying drawings,which are given by way of example only and not in any limitative sense.In these drawings:

FIG. 1 is a partial cross-section of the pump taken along the line I-Iof FIG. 2;

FIG. 2 is a section taken along the broken line lIII of FIG. 1;

FIGS. 3, 4 and 5 are diagrams illustrating the contours and theconstruction of cams employed in this application.

FIG. 1 shows only the portion of the pump which is concerned in thepresent invention.

The pump comprises a casing 1, a driving shaft 2 in said casing drivingthe barrel 3 with the piston 4. Each piston 4 is provided with a swivel5, the travel of which is controlled by a ring 6 driven in rotation andhaving shoes with flat faces in frictional contact with the obliqueswash-plate 7. The plate 7 is carried in known manner by two pivot pins8 and 9 which permit its obliquity to be varied. According to theinvention, this obliquity is controlled by two jacks 10 and 11, actingon the plate 7 through the intermediary of rocker-arms 12 and 13. Thejack 10, is composed of a cylinder 14 and a piston 15 and is suppliedwith pressure fluid through a conduit system 16 through the annulargroove 17, the bore 18, the chamber 19 and the bore 20. In the same way,the jack 11, composed of cylinder 21 and the piston 22 is supplied withpressure fluid through a conduit system 23 through the annular groove24, the bore 25, the chamber 26 and the bore 27 (in the rear position ofthe piston). The supply of the jacks 10 and 11 by the conduit system 16and 23 is effected by any suitable system of regulation control. Therocker-arms 12 and 13 pivot on shafts 28 and 29 supported in thecasing 1. The shafts 28 and 29 are preferably mounted in a rotatingring, formed in one or two parts, which always ensures a straight-linecontact between the bearing surfaces and rollers which will be describedlater, and the surfaces of the members with which the said bearingsurfaces and rollers co-operate.

The rocker-arms 12 and 13 are actuated by the pistons 15 and 22,preferably through the intermediary of rollers 30 and 31. Therocker-arms 12 and 13 act on the plate 7 through the bearing surfaces 32and 33, which cooperate respectively with the bearing surfaces 34 and 35of the plate 7. The co-operating surfaces 32 and 34 ice on the one handand 33 and 35 on the other are calculated and formed in the same way asthe profiles of gear teeth, preferably as the involute of a circle, forexample as ground, corrected teeth as shown in FIG. 3.

In FIG. 3, the line of action 3637 of the piston 15 of the jack 10 andthe line of action 38-39 of the piston 22 of the jack 11 arerespectively chosen as lines of pressure of the conventional outline ofthe involute of a circle. The plate 7 is shown at its mean position ofinclination, the extreme positions being shown at 40 and 41. There isthus obtained a rolling action without sliding and therefore withoutfriction, of the two rocker-arms 12 and 13 on the plate 7. Furthermore,the result is also obtained that the forces are respectively appliedalong the lines 3637 and 38-39, that is to say along the lines of actionof the jacks 10 and 11, thus avoiding any oblique force andcorresponding abnormal friction and wear. I

The invention provides for the profiles to be corrected so as to takeaccount of deformations of tooth form, and eventually so as to ensureequal travel of the two jacks 1i) and 11 when their operation makes thisnecessary. The invention is equally well applicable however to two jackshaving unequal travel, to two jacks having pistons of differentdiameters, or to two push-rods or two cams actuated in any known manner.

In FIG. 4, the lines a and 12 represent the limits of the bearingsurfaces 34 and 35 of the surface of the plate 7 which cooperate withthe bearing surfaces 32 and 33 of the rocker-arm. 42 and 42a, 43 and43a, are the flanks of the tooth, rounded by the milling of the plate.

Instead of machining the bearing surfaces 34 and 35 on the plate 7itself, as indicated above, the invention provides that these groundsurfaces may be machined on separate parts secured to the plate as shownin FIG. 5, given by way of example and without limitation. A milledportion 44, formed in the plate 7, receives the separate piece 45. Thispiece 45 is provided with a centering lug 46 engaged in a correspondinghole in the plate. On the piece 45, the surface 34 is machined, whichco-operates with the bearing surface 32 of the rocker-arm.

The invention also contemplates that the rollers and the bearingsurfaces of the rocker-arms may be interchanged one with the other, therollers being place on the plate side and the bearing surfaces on thejack side, or that the rollers on the jack side may be replaced byhearing surfaces similar to those described and also cooperating withbearing surfaces of corresponding profile, formed on the pistons of thejacks.

What I claim is:

1. A pump of the barrel type with a variable output comprising a platesupported for rotation about a transverse axis perpendicular to the axisof rotation of the pump, flat faces of shoes in frictional contact withthe plate, pistons supported for reciprocal movement, means swivelmounting said shoes on said pistons, a thrust member on each side ofsaid transverse axis adapted to transmit thrust force to said plate in adirection parallel to the axis of rotation of the pump to regulateinclination of the plate and in consequence thereof travel of thepistons, a transmission member between each said thrust member and saidplate movable in rotation about an axis of rotation parallel to the axisof rotation of the plate and including two bearing surfaces respectivelytangent to the thrust member and to the plate at points of contact lyingon a line substantially parallel to said transverse axis, each saidthrust member and plate including a bearing surface at least one ofwhich is in contact with a bearing surface of the transmission memberand which latter surfaces have profile contours corresponding to theflanks of two teeth of the same gear-Wheel.

2. A pump as claimed in claim 1, in which a bearing surface of thetransmission member and the cooperating surface of the plate haverespectively the profiles of the flanks of the teeth of two wheels of agear, having axes corresponding respectively with the axes of rotationof the transmission member and of the plate.

3. A'pump as claimed in claim 2, in which the bearing surface of thetransmission member on the thrust member is a roller having an axis ofrotation which is parallel to the axis of rotation of said transmissionmember.

I 4. A pump as claimed in claim 2, in which the bearing surface of thetransmission member and that of the thrust member are respectively thatof the flank of a tooth of a toothed wheel having an axis which iscoincident with the axis of rotation of said member and that of theflank of a tooth of a toothed rack extending parallel to the axis of thepump, and engaging with said wheel.

, 5. A pump as claimed in claim 1, in which the bearing surface of saidthrust member and the co-operating surface of said transmission memberare respectively that of the flank of a tooth of a toothed rackextending parallel to the axis of the pump and that of a wheel having anaxis coincident with that of the transmission member and engaging withsaid toothed rack, the bearing surface of said transmission membercooperating with the plate being the surface of a roller having an axisparallel to the axis of rotation of said transmission member.

6. A pump as claimed in claim 1, in which said thrust member is thepiston of a hydraulic jack.

7. A pump as claimed in claim 1 comprising a separate part having asurface constituting the said one bearing surface which has a contourcorresponding to the flank of the gear teeth, said separate partincluding a centering lug for being accommodated in the element which isto have the bearing surface corresponding to the flank of the gearteeth.

References Cited in the file of this patent UNITED STATES PATENTS304,971 Strong Sept. 9, .1884 1,945,391 Benedek Jan. 30, 1934 2,896,546Lundgren et al. July 28, 1959

1. A PUMP OF THE BARREL TYPE WITH A VARIABLE OUTPUT COMPRISING A PLATESUPPORTED FOR ROTATION ABOUT A TRANSVERSE AXIS PERPENDICULAR TO THE AXISOF ROTATION OF THE PUMP, FLAT FACES OF SHOES IN FRICTIONAL CONTACT WITHTHE PLATE, PISTONS SUPPORTED FOR RECIPROCAL MOVEMENT, MEANS SWIVELMOUNTING SAID SHOES ON SAID PISTONS, A THRUST MEMBER ON EACH SIDE OFSAID TRANSVERSE AXIS ADAPTED TO TRANSMIT THRUST FORCE TO SAID PLATE IN ADIRECTION PARALLEL TO THE AXIS OF ROTATION OF THE PUMP TO REGULATEINCLINATION OF THE PLATE AND IN CONSEQUENCE THEREOF TRAVEL OF THEPISTONS, A TRANSMISSION MEMBER BETWEEN EACH SADI THRUST MEMBER AND SAIDPLATE MOVABLE IN ROTATION OF THE PLATE AND INCLUDING TWO BEARINGSURFACES RESPECTIVELY TANGENT TO THE THRUST MEMBER AND TO THE PLATE ATPOINTS OF CONTACT LYING ON A LINE SUBSTANTIALLY PARALLEL TO SAIDTRANSVERSE AXIS, EACH SAID THRUST MEMBER AND PLATE INCLUDING A BEARINGSURFACE AT LEAST ONE OF WHICH IS IN CONTACT WITH A BEARING SURFACE OFTHE TRANSMISSION MEMBER AND WHICH LATTER SURFACES HAVE PROFILE CONTOURSCORRESPONDING TO THE FLANKS OF TWO TEETH OF THE SAME GEAR-WHEEL.